1. Field
The present application relates to a liquid crystal display (LCD), and more particularly, to an LCD including a liquid crystal layer interposed between display substrates.
2. Description of the Related Art
Liquid crystal displays (LCDs) are one of the most widely used types of flat panel displays. Generally, an LCD includes a pair of display substrates having electric field generating electrodes such as pixel electrodes and a common electrode and a liquid crystal layer interposed between the display substrates. The LCD generates an electric field in the liquid crystal layer by applying voltages to the electric field generating electrodes. Accordingly, the alignment of liquid crystal molecules of the liquid crystal layer is determined, and polarization of incident light is controlled. As a result, an image is displayed on the LCD.
In the LCD, a polarizing plate is attached to an outer surface of each of the two display substrates having the electric field generating electrodes in order to adjust polarization of incident light. The polarizing plate is an absorptive polarizing plate that absorbs all light excluding light of a desired polarization. Due the polarizing plate, only a very small portion of a light source which supplies light to the LCD can be used to display an image. Accordingly, this reduces the light efficiency of the light source of the LCD.
To improve the light efficiency of the light source of the LCD, a wire grid polarizer (WGP) is formed using a nanoimprint method.
The WGP is an optical device that extracts linearly polarized light having a specific. oscillation direction from unpolarized light such as natural light. That is, when a period of the arrangement of metal wires is shorter than a half wavelength of an incident electromagnetic wave, a polarization component (S wave) parallel to the metal wires is reflected, and a polarization component (P wave) perpendicular to the metal wires is transmitted. Using this phenomenon, a planar polarizer having superior polarization efficiency, high transmittance, and a wide viewing angle can he manufactured. Here, the planar polarizer is called a WGP.
If the WGP is applied to a thin-film transistor (TFT) backplane, a luminance improvement effect can he obtained due to a recycling effect for S waves. However, the WGP typically made of a metal material may affect characteristics of a TFT formed thereon. To prevent this problem, a TFT process begins after a WGP insulating layer is formed. However, since a metal wiring line is formed on the WGP insulating layer, a defect may occur in a pad portion due to an adhesion problem.